Apparatus and method for sealing an electrical connector

ABSTRACT

A connector comprises a substantially cylindrical housing having an internal circumferential groove therein. A seal element is disposed within the housing, the seal element having an axial passage therethrough. A plurality of circumferential sealing lips are spaced apart along the axial passage and sized such that each of the plurality of circumferential sealing lips provides a compression seal along a cable element inserted through the axial passage. A follower abuts the seal element. A spring is disposed in the groove acting against the follower and forcing the follower against the seal to maintain a fluid seal on the cable element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part of U.S. application Ser. No.11/536,116 filed Sep. 28, 2006, which is a Continuation-in-Part of U.S.application Ser. No. 11/458,939 filed Jul. 20, 2006, which claimspriority from U.S. Provisional Application 60/812,887 filed on Jun. 12,2006, each of which is incorporated herein by reference.

BACKGROUND

1. Field of the Invention

The present invention relates to the field of electrical connectors andmore particularly to sealing of conductors therein.

2. Background Information

Numerous applications involve the use of electrical connectors. Highpower connectors are used in applications including subsea connections,and in submersible pump connections in both water wells and oil wells.The size, weight, and orientation of the cables and connectors inducemechanical loads on connector components that make reliable mechanicaland electrical connection difficult. In addition, the physicalenvironment may include high temperature, high pressure, and abrasiveand/or corrosive fluids, including liquids and gases.

The sealing of the electrical conductors in the connector from thesurrounding fluids is crucial in such high power applications.

SUMMARY

In one aspect of the present invention, a connector comprises asubstantially cylindrical housing having an internal circumferentialgroove therein. A seal element is disposed within the housing, the sealelement having an axial passage therethrough. A plurality ofcircumferential sealing lips are spaced apart along the axial passageand sized such that each of the plurality of circumferential sealinglips provides a compression seal along a cable element inserted throughthe axial passage. A follower abuts the seal element. A spring isdisposed in the groove acting against the follower and forcing thefollower against the seal to maintain a fluid seal on the cable element.

In another aspect, a method for sealing a cable comprises forming aplurality of sealing lips spaced apart along an axial passage of anelastomeric seal element. Each of the plurality of sealing lips is sizedsuch that each of the plurality of sealing lips provides a compressionseal along a cable element inserted through the axial passage. Afollower applies force against the elastomeric seal element to maintainthe compression seal along the cable element.

Non-limiting examples of certain aspects of the invention have beensummarized here rather broadly, in order that the detailed descriptionthereof that follows may be better understood, and in order that thecontributions they represent to the art may be appreciated. There are,of course, additional features of the invention that will be describedhereinafter.

BRIEF DESCRIPTION OF THE FIGURES

For a detailed understanding of the present invention, references shouldbe made to the following detailed description of the exemplaryembodiment, taken in conjunction with the accompanying drawings, inwhich like elements have been given like numerals, wherein:

FIG. 1 shows an exploded view of a connector contact assembly accordingto one illustrative embodiment of the present invention;

FIG. 2 shows an assembled view of the elements of FIG. 1;

FIG. 3 shows a portion of a contact receptacle according to oneillustrative embodiment of the present invention;

FIG. 4A shows an end view of a gripping contact according to oneillustrative embodiment of the present invention;

FIG. 4B shows a cross-section view along section line A-A of FIG. 4A;

FIG. 5 shows a non-limiting example of a portion of a connector assemblyaccording to one illustrative embodiment of the present invention;

FIG. 6 shows a non-limiting example of a connector utilizing a contactassembly of one embodiment of the present invention to connect power toa submersible pump;

FIG. 7 is a sketch showing a seal element having a cable insertedthrough a passageway in the seal element;

FIG. 8A is a cross section of the seal element of FIG. 7;

FIG. 8B is an end view of the seal element of FIG. 7;

FIG. 8C is an enlarged view of bubble A of FIG. 8B;

FIG. 9 a is a sketch of a seal element having an insert;

FIG. 9B is a sketch of the insert of FIG. 9A;

FIG. 10 is a sketch of a connector comprising a wave spring forcing afollower against the seal element;

FIG. 11 is a sketch of a connector comprising a disc spring forcing afollower against the seal element; and

FIG. 12 is a sketch of a connector comprising a coil spring forcing afollower against the seal element.

DETAILED DESCRIPTION

The following description presents non-limiting examples of embodimentsof the present invention. Refer now to FIGS. 1-4B. FIG. 1 shows anexploded view of a connector contact assembly 5 according to oneillustrative embodiment of the present invention. As shown in FIG. 1, acable 40 has an electrical conductor 45 therein. Electrical conductor 45may be a solid conductor, or, alternatively, a stranded conductor.

A gripping contact 15 has a cavity 16 sized to accept electricalconductor 45. In one embodiment, the inner diameter of cavity 16 is asubstantially a zero clearance fit with the outer diameter of electricalconductor 45. Gripping contact 15 (see also FIGS. 4A and 4B) comprises aplurality of gripping fingers 20 with an outer surface 25 having asubstantially conical shape. As seen, in FIG. 4B, the conical surface 25is defined by angle β. In one embodiment, angle β is about 6°.Alternatively, angle β may be in the range of about 2° to about 10°. Theinternal surface 21 of fingers 20 substantially defines cavity 16. Whileshown in FIG. 4A as comprising four fingers, any number of fingers maybe used and are intended to be encompassed by the present disclosure. Inone embodiment, the internal surface 21 of fingers 20 may besubstantially smooth. Alternatively, in another embodiment, the internalsurface 21 of fingers 20 may have a raised pattern (not shown) formed onsurface 21. Such a pattern may include, but is not limited to: a threadform, a tooth form, a knurling form, and any other raised pattern formused for gripping electrical conductor 45.

On an opposite end of gripping contact 15, an integral body 27 has aninternally threaded bore 35. Gripping contact 15 may be made out of anelectrically conductive metal. Examples of such an electricallyconductive metal include, but are not limited to: gold, silver, copper,copper alloys, aluminum, aluminum alloys, brass, bronze, and any othersuitable electrically conducting metal. The surfaces 25 and 21 offingers 20 may be plated with a suitable electrically conductivematerial to reduce galling and/or wear of the gripping fingers 20. Anysuitable plating may be used including, but not limited to: chromeplating, nickel plating, gold plating, and silver plating.

A contact receptacle 10 (see FIGS. 1-3), has an internal conical surface26 having an angle α where α≦β. In one embodiment, α is about 1.0°smaller than β. Alternatively, α may be smaller than β from about 0.5°to about 1.5°. The difference in angles ensures that fingers 20 ofgripping contact 15 are forced to collapse around and compresselectrical conductor 45, as shown in FIGS. 1 and 2, when grippingcontact 15 is urged axially into contact receptacle 10. Contactreceptacle 10 may be made from any of the materials as describedpreviously for gripping contact 15. Similarly, contact receptacle 10 maybe plated by any of the platings discussed previously with respect togripping contact 15.

As shown in FIGS. 1 and 2, threaded element 30 engages threads 35 ingripping contact 15 and, under tension, reacts against shoulder 31 incontact receptacle 10 such that gripping contact 15 is axially urgedinto contact receptacle 10. This motion causes interaction between outersurface 25 and inner surface 26 such that fingers 20 of gripping contact15 are forced to collapse around and compress electrical conductor 45along substantially the length of the extension of electrical conductor45 into gripping contact 15. The use of threaded element 30 provides asubstantially repeatable force urging gripping contact 15 into contactreceptacle 10, thereby providing a repeatable holding force betweenelectrical contact 45 and connector contact assembly. In addition, thesubstantially repeatable axial holding force provides a repeatableelectrical contact between fingers 20 of gripping contact 15 and bothelectrical conductor 45 and contact receptacle 10. Threaded element 30may be a suitably sized threaded fastener that may be commerciallyavailable. Alternatively, threaded element 30 may be designed for thisparticular application using techniques known in the art.

FIG. 5 depicts a non-limiting example of a portion of a connectorassembly 100 according to one illustrative embodiment of the presentinvention. Connector assembly 100 may be a power connector for use inconnecting a power source to a submersible pump in a well.Alternatively, connector assembly 100 may be a sub-sea connector. Asshown in FIG. 5, a multi-conductor armored cable assembly 41 has atleast one insulated cable 40 with an internal electrical conductor 45.Armored cable assembly 41 is connected to connector assembly 100 bycable adapter 101. Crossover 102 connects cable adapter 101 to lowerhousing 103.

It will be appreciated by one skilled in the art that the portion ofconnector assembly 100 shown in FIG. 5 may be immersed in a highpressure fluid such as, for example, in a wellbore. To seal highpressure fluid from the internal electrical connections, cable 40 isinserted through seal 120. Seal 120 is an elastomer seal that iscompressed around the insulation of cable 40 to preclude passage offluid toward the electrical contacts 15 and 10. Seal 120 is held inplace by follower 130. Seal 120 may be made of a suitable elastomer.Suitable elastomers include but are not limited to, natural rubber,synthetic rubber, fluoroelastomers, perfluoroelastomers, ethylenepropylene diene rubber (EPDM), and any other suitable elastomer.

Connector contact assembly 5 is inserted into an insulator 110 that islocated above seal 120. As shown, connector contact assembly 5 comprisesgripping contact 15 assembled in contact receptacle 10 and held in placeby threaded element 30. To better facilitate field assembly, insulator110 is located in lower housing 103 and upper housing 104 that areconnected through coupling nut 140 and shoulder nut 135 acting againstshoulder 145. Insulator 110 may be a thermoplastic suitable for theparticular environment encountered. Examples of such a thermoplasticinclude, but are not limited to, a polyetheretherketone material and aglass-filled polyetheretherketone material. Gripping contact 15 is inengaged contact, both mechanically and electrically with electricalconductor 45. Connector assembly 5 conducts an electrical power signalto contact 105 which is electrically conducted to a surface powercontrol system. One skilled in the art will appreciate that theconnector assembly 5 and its components may be appropriately scaled tofit different size electrical conductors without undue experimentation.

One non-limiting example of an application of the present invention isshown in FIG. 6. In FIG. 6, a well 200 comprises a string of surfacepipe 212 cemented in the upper portion of a bore hole 214 which extendsinto the earth to a location adjacent and usually below a subterraneanoil productive formation (not shown). A wellhead 216 attaches to thesurface pipe 212. A set of slips 218 suspends a casing string 220 insidethe bore hole 214 which is also cemented in place. A casing head 222connects to the upper end of the casing string 220 and includes a tubinghanger 224.

A tubing string 226 is suspended from the tubing hanger 224 and extendsdownwardly inside the casing string 220 to a location adjacent theproductive formation. An electrically powered submersible pump 228, ofany suitable type, on the lower end of the tubing string 226 pumps oilor an oil-water mixture from the inside of the casing string 220upwardly through the tubing string 226.

Electric power is delivered to the downhole pump 228 through an armoredcable 234 connected to a motor 236 comprising part of the submersiblepump 228. The cable 234 extends upwardly in the well 210 to a connector100 of the present invention located immediately below the tubing hanger224. The connector 100 is secured to a mandrel or feed through socket240 extending through the hanger 224, seal assembly 230 and flange 232.The connector 100 employs a contact assembly as described previously. Inone embodiment, a pig tail connector 242 attaches the mandrel 240 to apower cable 244 extending to a source of power at the surface. Whiledescribed above as used in a submersible pump application, it isintended that the present invention encompass all applications requiringhigh electrical power transmission. Such applications include, but arenot limited to: electrical motor connectors, transformer connectors,electrical generator connectors, welding machine connectors, and anyother such electrical and/or electromagnetic devices.

In one illustrative embodiment, FIGS. 7-8C show elastomer seal element120, with cable 40 extending through an axial passage 211 in sealelement 120. Cable 40 has an insulating sheath 200 covering conductor45. Seal element 120 has a substantially cylindrical seal body 121 thatfits closely in housing 103. Seal element 120 also has an integral boot211 extending outward from seal body 121. Boot 211 is sized to receivecable 40. As shown in FIG. 8B, seal 120 may have multiple passages 211for receiving multiple cables 40. As discussed previously, seal 120 maybe made of any suitable elastomer. Suitable elastomers include but arenot limited to, natural rubber, synthetic rubber, fluoroelastomers,perfluoroelastomers, ethylene propylene diene rubber (EPDM), and anyother suitable elastomer. It is intended that the present inventionencompass any number of conductors that may be accommodated within agiven housing geometry.

Boot 211 is exposed to the ambient fluid in the proximity of theinstalled connector 100 (see the preceding discussion relating to FIGS.5 and 6). Spaced apart along the internal surface of passage 211 is aplurality of sealing lips 220. As seen in FIGS. 7-8C, each sealing lip220 has a recessed surface 222 adjacent thereto. Sealing lip 220extends, in an undeformed state, a distance L above recessed surface222, where L is in the range of about 0.010 to about 0.030 inches. Inone embodiment, sealing lip 220 has a substantially conical form in anundeformed state such that sealing lip 220 forms an angle θ withrecessed surface 222, where angle θ is in the range of about 5 to about15 degrees.

In one non-limiting example, the sealing lips 220 have an initialcompression against insulator 200 in the range of about 5-15%, therebyproviding an initial fluid seal at the interface between sealing lip 220and insulator 200. As increasing external fluid pressure acts on theouter surface of boot 211, the elastomer material of boot 211 is furthercompressed against insulator 200 of cable 40. As the fluid pressureincreases, boot 211 is increasingly compressed against insulator 200.The increased compression causes sealing lip 220 to flatten out againstinsulator 200, thereby increasing the sealing area as the fluid pressureis increased. The flattening of lip 220 also causes the edge of lip 220to encroach into the cavity bounded by the insulator 200, recessedsurface 222, and lip 220. The same process occurs at each lip 220 alongboot 210. The plurality of seal lips 220 generates multiple redundantseals along boot 210 to prevent the incursion of contaminated fluid 202along the interface between boot 210 and insulator 200.

FIG. 7 also shows a conductor boot 212 extending axially toward theopposite direction from boot 210. As shown in FIG. 5, conductor boot 212fits into insulator 110 where conductor 45 is coupled to grippingcontact 15. As shown in FIG. 4A, gripping contact 15 has several slottedfingers facing conductor boot 212. When high fluid pressure P (see FIG.7), acts against surface 123 of seal 120, seal 120 is forced axially inhousing 103 (see FIG. 5) such the end of conductor boot 212 may beextruded into the slots in gripping contact 15. In one embodiment, ananti-extrusion washer 214 is attached to the end of conductor boot 212.Anti-extrusion washer 214 is made of an insulating material such as, forexample, an elastomer or a thermoplastic. Any suitable elastomer orthermoplastic having a suitable hardness to prevent extrusion under highpressure may be used. For example, elastomers having a Shore A durometergreater than 70 may be used. In one embodiment, washer 214 may beadhesively attached to the end of conductor boot 212. Alternatively,washer 214 may be molded into the end of conductor boot 212 duringmanufacture of conductor boot 212.

In another embodiment, see FIG. 9, seal 320 is similar in dimensions topreviously described seal 120 and may be used interchangeably with seal120 in connector 100. Seal 320 has integral boot 211 molded on one sideand an insert 321 molded into an opposite side. Insert 321 has at leastone conductor boot 312 molded therein. Insert 321 may be of an elastomermaterial that is different than the elastomer material of seal 320. Inone example, the elastomer material of insert 321 may be an EPDMmaterial having a Shore A hardness in the range of 70-80. The materialof insert 321 is substantially harder than the material of the body 319of seal 320. The additional hardness acts to reduce extrusion ofconductor boot 312 into the facing slots in gripping contact 15 asdescribed previously.

As described above, the various embodiments of the present invention maybe immersed in a fluid environment that experiences extreme pressuresand temperatures. For example, temperatures may exceed 500° F. andpressures may exceed 20,000 PSI. In addition, the pressure andtemperature may vary over time. These extreme conditions and theirpossible time variations require active techniques for maintaining afluid seal as the conditions vary. In one example, considering anelastomeric seal and a metallic housing, as the temperature of thesurrounding environment increases, the diameter of seal element 120expands more than the diameter of housing 103 due to the difference inthermal expansion coefficients of seal 120 and housing 103. The radialrestraint of the expansion causes substantial stresses to build up inseal 120. As the stresses increase, seal 120 will expand axially, due toPoisson's effect, to relieve the radial stress. The axial length ofgroove 132 is chosen to provide sufficient length to accommodate theseal's axial expansion. Conversely, when the surrounding temperature isreduced, seal 120 contracts more than housing 103 and may no longerprovide sufficient radial squeeze on cable 40 and/or housing 103 toaffect a fluid seal. Pressure effects may have similar effects. Forexample, at high pressures, the fluid pressure acts against the fluidexposed face of seal 120, compressing the seal axially. This loadingresults in radial expansion of the seal due to Poisson's effect. Rapidlowering of the pressure may relax the radial squeeze on both housing103 and/or cable 40 such that there is no longer sufficient sealinginteraction at one or both locations. In order to allow for the changingconditions, in another embodiment of the present invention, see FIG. 10,spring 131 is disposed in groove 132 and applies a force throughfollower 130 to seal 120. The axial length of groove 132 is sufficientto accommodate the axial expansion. The spring force applied to seal 120is sufficient to radially expand seal 120 to maintain a seal on cable 40and housing 103 in the presence of thermal and/or pressure cycling ofthe surrounding environment. In the embodiment shown in FIG. 10, spring131 is a wave spring, for example a wave spring commercially availablefrom the Smalley Steel Ring Company of Lake Zurich, Ill. Multiplesprings may be stacked together to provide suitable loading andexpansion travel. In one example, a wave spring exerts a force of up to40 lbf on follower 130, and provides a travel distance of 0.030 in.

In another example, see FIG. 11, one or more disc springs 231, alsocalled Belleville springs, may be disposed in groove 232 to apply forceto follower 130.

In yet another example, see FIG. 12, a plurality of individual coilsprings 331 may be disposed around the periphery of groove 332 to applyforce to follower 130.

While the foregoing disclosure is directed to the non-limitingillustrative embodiments of the invention presented, variousmodifications will be apparent to those skilled in the art. It isintended that all variations within the scope of the appended claims beembraced by the foregoing disclosure.

1. A connector comprising: a substantially cylindrical housing having aninternal circumferential groove therein; a seal element disposed withinthe housing, the seal element having an axial passage therethrough; aplurality of circumferential sealing lips spaced apart along the axialpassage and sized such that each of the plurality of circumferentialsealing lips provides a compression seal along a cable element insertedthrough the axial passage; a follower abutting the seal element; and aspring disposed in the groove acting on the follower, the spring forcingthe follower against the seal element to maintain a fluid seal on thecable element.
 2. The connector of claim 1 wherein the seal element ismade of an elastomer chosen from the group consisting of: a naturalrubber, a synthetic rubber, a fluoroelastomer, a perfluoroelastomer, andan ethylene propylene diene rubber.
 3. The connector of claim 1 whereinthe seal element further comprises a pair of opposed sealing lips havinga recessed surface therebetween.
 4. The connector of claim 1 wherein aninitial compression of the plurality of circumferential sealing elementsagainst the cable element is in the range of 5-15%.
 5. The connector ofclaim 1 wherein at least one sealing lip is located in a boot integralto the seal element.
 6. The connector of claim 3 wherein a fluidpressure acting on an outer diameter surface of the boot furthercompresses each of the plurality of sealing lips around the cableelement.
 7. The connector of claim 1 wherein each of the plurality ofsealing lips comprises a substantially conical surface.
 8. The connectorof claim 7 wherein the substantially conical surface has an initialangle in the range of 5-15 degrees.
 9. The connector of claim 1 furthercomprising an insert molded into the seal element, the insert having aconductor boot molded therein.
 10. The connector of claim 9 wherein theseal element is made of a first elastomer material and the insert ismade of a second elastomer material that is harder than the firstelastomer material.
 11. The connector of claim 1 wherein the springcomprises a coil spring.
 12. The connector of claim 1 wherein the springcomprises a slanted coil spring.
 13. The connector of claim 1 whereinthe spring comprises a wave spring.
 14. The connector of claim 1 whereinthe spring comprises a belleville spring.
 15. The connector of claim 1wherein the follower is axially constrained in the groove.
 16. A methodfor sealing a cable, comprising: forming a plurality of sealing lipsspaced apart along an axial passage of an elastomeric seal element;sizing each of the plurality of sealing lips such that each of theplurality of sealing lips provides a compression seal along a cableelement inserted through the axial passage; and forcing a followeragainst the elastomeric seal element to maintain the compression sealalong the cable element.
 17. The method of claim 19, further comprising:locating at least a portion of the plurality of sealing lips along anaxial passage of a boot integrally connected to the elastomer sealelement such that fluid pressure on an external surface of the bootincreases the compression of the sealing lips on the cable element. 18.The method of claim 16 wherein forcing the follower against theelastomeric seal element comprises applying a spring force against thefollower.
 19. The method of claim 18 wherein the spring force isgenerated by a wave spring.
 20. The method of claim 18 wherein thespring force is generated by a coil spring.